Carpal tunnel syndrome

Overview

Carpal tunnel syndrome is a condition that causes numbness, tingling and other symptoms in the hand and arm. Carpal tunnel syndrome is caused by a compressed nerve in the carpal tunnel, a narrow passageway on the palm side of your wrist.

Proper treatment usually relieves the tingling and numbness and restores wrist and hand function.

Symptoms

Carpal tunnel syndrome symptoms usually start gradually. The first symptoms often include numbness or tingling in your thumb, index and middle fingers that comes and goes.

Carpal tunnel syndrome may also cause discomfort in your wrist and the palm of your hand. Common carpal tunnel syndrome symptoms include:

Tingling or numbness. You may experience tingling and numbness in your fingers or hand. Usually the thumb and index, middle or ring fingers are affected, but not your little finger. Sometimes there is a sensation like an electric shock in these fingers.

The sensation may travel from your wrist up your arm. These symptoms often occur while holding a steering wheel, phone or newspaper. The sensation may wake you from sleep.

Many people "shake out" their hands to try to relieve their symptoms. The numb feeling may become constant over time.

Weakness. You may experience weakness in your hand and a tendency to drop objects. This may be due to the numbness in your hand or weakness of the thumb's pinching muscles, which are also controlled by the median nerve.

When to see a doctor

See your doctor if you have persistent signs and symptoms suggestive of carpal tunnel syndrome that interfere with your normal activities and sleep patterns. Permanent nerve and muscle damage can occur without treatment.

Causes

Carpal tunnel syndrome is caused by pressure on the median nerve.

The median nerve runs from your forearm through a passageway in your wrist (carpal tunnel) to your hand. It provides sensation to the palm side of your thumb and fingers, except the little finger. It also provides nerve signals to move the muscles around the base of your thumb (motor function).

Anything that squeezes or irritates the median nerve in the carpal tunnel space may lead to carpal tunnel syndrome. A wrist fracture can narrow the carpal tunnel and irritate the nerve, as can the swelling and inflammation resulting from rheumatoid arthritis.

There is no single cause in many cases. It may be that a combination of risk factors contributes to the development of the condition.

Risk factors

A number of factors have been associated with carpal tunnel syndrome. Although they may not directly cause carpal tunnel syndrome, they may increase your chances of developing or aggravating median nerve damage. These include:

Anatomic factors. A wrist fracture or dislocation, or arthritis that deforms the small bones in the wrist, can alter the space within the carpal tunnel and put pressure on the median nerve.

People with smaller carpal tunnels may be more likely to have carpal tunnel syndrome.

Sex. Carpal tunnel syndrome is generally more common in women. This may be because the carpal tunnel area is relatively smaller in women than in men.

Women who have carpal tunnel syndrome may also have smaller carpal tunnels than women who don't have the condition.

Nerve-damaging conditions. Some chronic illnesses, such as diabetes, increase your risk of nerve damage, including damage to your median nerve.

Inflammatory conditions. Illnesses that are characterized by inflammation, such as rheumatoid arthritis, can affect the lining around the tendons in your wrist and put pressure on your median nerve.

Obesity. Being obese is a significant risk factor for carpal tunnel syndrome.

Alterations in the balance of body fluids. Fluid retention may increase the pressure within your carpal tunnel, irritating the median nerve. This is common during pregnancy and menopause. Carpal tunnel syndrome associated with pregnancy generally resolves on its own after pregnancy.

Workplace factors. It's possible that working with vibrating tools or on an assembly line that requires prolonged or repetitive flexing of the wrist may create harmful pressure on the median nerve or worsen existing nerve damage.

However, the scientific evidence is conflicting and these factors haven't been established as direct causes of carpal tunnel syndrome.

Several studies have evaluated whether there is an association between computer use and carpal tunnel syndrome. However, there has not been enough quality and consistent evidence to support extensive computer use as a risk factor for carpal tunnel syndrome, although it may cause a different form of hand pain.

Prevention

There are no proven strategies to prevent carpal tunnel syndrome, but you can minimize stress on your hands and wrists with these methods:

Reduce your force and relax your grip. If your work involves a cash register or keyboard, for instance, hit the keys softly. For prolonged handwriting, use a big pen with an oversized, soft grip adapter and free-flowing ink.

Take frequent breaks. Gently stretch and bend hands and wrists periodically. Alternate tasks when possible. This is especially important if you use equipment that vibrates or that requires you to exert a great amount of force.

Watch your form. Avoid bending your wrist all the way up or down. A relaxed middle position is best. Keep your keyboard at elbow height or slightly lower.

Keep your hands warm. You're more likely to develop hand pain and stiffness if you work in a cold environment. If you can't control the temperature at work, put on fingerless gloves that keep your hands and wrists warm.

Diagnosis

Your doctor may ask you questions and conduct one or more of the following tests to determine whether you have carpal tunnel syndrome:

History of symptoms. Your doctor will review the pattern of your symptoms. For example, because the median nerve doesn't provide sensation to your little finger, symptoms in that finger may indicate a problem other than carpal tunnel syndrome.

Carpal tunnel syndrome symptoms usually occur include while holding a phone or a newspaper, gripping a steering wheel, or waking up during the night.

Physical examination. Your doctor will conduct a physical examination. He or she will test the feeling in your fingers and the strength of the muscles in your hand.

Bending the wrist, tapping on the nerve or simply pressing on the nerve can trigger symptoms in many people.

X-ray. Some doctors recommend an X-ray of the affected wrist to exclude other causes of wrist pain, such as arthritis or a fracture.

Electromyogram. This test measures the tiny electrical discharges produced in muscles. During this test, your doctor inserts a thin-needle electrode into specific muscles to evaluate the electrical activity when muscles contract and rest. This test can identify muscle damage and also may rule out other conditions.

Nerve conduction study. In a variation of electromyography, two electrodes are taped to your skin. A small shock is passed through the median nerve to see if electrical impulses are slowed in the carpal tunnel. This test may be used to diagnose your condition and rule out other conditions.

Treatment

Treat carpal tunnel syndrome as early as possible after symptoms start.

Take more frequent breaks to rest your hands. Avoiding activities that worsen symptoms and applying cold packs to reduce swelling also may help.

Other treatment options include wrist splinting, medications and surgery. Splinting and other conservative treatments are more likely to help if you've had only mild to moderate symptoms for less than 10 months.

Nonsurgical therapy

If the condition is diagnosed early, nonsurgical methods may help improve carpal tunnel syndrome, including:

Wrist splinting. A splint that holds your wrist still while you sleep can help relieve nighttime symptoms of tingling and numbness. Nighttime splinting may be a good option if you're pregnant.

Nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs, such as ibuprofen (Advil, Motrin IB, others), may help relieve pain from carpal tunnel syndrome in the short term.

There isn't evidence, however, that these drugs improve carpal tunnel syndrome.

Corticosteroids. Your doctor may inject your carpal tunnel with a corticosteroid such as cortisone to relieve pain. Sometimes your doctor uses an ultrasound to guide these injections.

Corticosteroids decrease inflammation and swelling, which relieves pressure on the median nerve. Oral corticosteroids aren't considered as effective as corticosteroid injections for treating carpal tunnel syndrome.

If carpal tunnel syndrome is caused by rheumatoid arthritis or another inflammatory arthritis, then treating the arthritis may reduce symptoms of carpal tunnel syndrome. However, this is unproved.

Surgery

Surgery may be appropriate if your symptoms are severe or don't respond to other treatments.

The goal of carpal tunnel surgery is to relieve pressure by cutting the ligament pressing on the median nerve.

The surgery may be performed with two different techniques:

Endoscopic surgery. Your surgeon uses a telescope-like device with a tiny camera attached to it (endoscope) to see inside your carpal tunnel. Your surgeon cuts the ligament through one or two small incisions in your hand or wrist.

Endoscopic surgery may result in less pain than does open surgery in the first few days or weeks after surgery.

Open surgery. Your surgeon makes an incision in the palm of your hand over the carpal tunnel and cuts through the ligament to free the nerve.

Discuss the risks and benefits of each technique with your surgeon before surgery. Surgery risks may include:

Incomplete release of the ligament

Wound infections

Scar formation

Nerve or vascular injuries

During the healing process after the surgery, the ligament tissues gradually grow back together while allowing more room for the nerve. This internal healing process typically takes several months, but the skin heals in a few weeks.

Carpal tunnel release

During carpal tunnel release, a surgeon makes an incision in the palm of your hand over the carpal tunnel ligament and cuts through the ligament to relieve pressure on the median nerve. The surgery may be done by making one incision on the palm side of the wrist, or by making several small incisions.

Lifestyle and home remedies

These steps may provide temporary symptom relief:

Take short breaks from repetitive activities involving the use of your hands.

Lose weight if you are overweight or obese.

Rotate your wrists and stretch your palms and fingers.

Take a pain reliever, such as aspirin, ibuprofen (Advil, Motrin IB, others) or naproxen sodium (Aleve).

Wear a snug, not tight, wrist splint at night. You can find these over-the-counter at most drugstores or pharmacies.

Avoid sleeping on your hands.

If pain, numbness or weakness recurs and persists, see your doctor.

Alternative medicine

Integrate alternative therapies into your treatment plan to help you cope with carpal tunnel syndrome. You may have to experiment to find a treatment that works for you. Always check with your doctor before trying any complementary or alternative treatment.

Yoga. Yoga postures designed for strengthening, stretching and balancing the upper body and joints may help reduce pain and improve grip strength.

Hand therapy. Early research suggests that certain physical and occupational hand therapy techniques may reduce symptoms of carpal tunnel syndrome.

Ultrasound therapy. High-intensity ultrasound can be used to raise the temperature of a targeted area of body tissue to reduce pain and promote healing. Research shows inconsistent results with this therapy, but a course of ultrasound therapy over several weeks may help reduce symptoms.